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Biomedical subjects

T Enomoto

Publications and source records attributed to T Enomoto.

At least 199 records · Page 11Linked to original sources
PubMed1994

Alteration of the p53 tumor suppressor gene occurs independently of K-ras activation and more frequently in serous adenocarcinomas than in other common epithelial tumors of the human ovary.

To clarify the role of the p53 tumor suppressor gene in the development of human ovarian epithelial tumors and to study the association of p53 alterations with K-ras activation, a series of 70 common epithelial ovarian tumors from Japanese patients was studied. These included 31 serous adenocarcinomas, 12 mucinous adenocarcinomas, 5 mucinous tumors of borderline malignancy, 13 endometrioid adenocarcinomas, and 9 clear cell carcinomas. Allelic loss, recognized at the polymorphic site in codon 72 of the p53 gene, was detected in 14 of 36 (39%) informative cases by restriction fragment length polymorphism analysis and by single-strand conformation polymorphism (SSCP) analysis of polymerase chain reaction (PCR)-amplified DNA fragments. Mutations in the highly conserved regions of the p53 gene were detected by SSCP analysis of PCR-amplified fragments. Mutations were found in 22 of 70 (31%) ovarian tumors, including 1 of 5 mucinous tumors of borderline malignancy. Mutations were subsequently characterized by direct sequencing. Single missense base substitutions were detected in 13 ovarian carcinomas and in one case of mucinous tumor of borderline malignancy. Short (1-8 bp) deletions and insertions were found in 8 cases. Mutations in the p53 gene occurred more frequently in serous adenocarcinomas (14/31, 45%) than in all nonserous types of malignant epithelial tumors combined (7/34, 21%; P = 0.032). Point mutations in K-ras were identified by dot blot hybridization analysis of PCR-amplified fragments with mutation-specific oligonucleotides and by direct sequencing. The overall frequency of K-ras mutations was 19/70 (27%). K-ras mutations were found in 12 of 17 (71%) mucinous tumors (8/12 mucinous carcinomas [67%] and 4/5 mucinous tumors of borderline malignancy [80%]), and occurred more frequently than in serous carcinomas (4/31, 13%; P = 0.00009) or in all nonmucinous types of ovarian epithelial tumors combined (7/53, 13%; P = 0.00002). These data suggest that different combinations of oncogenes and/or tumor suppressor genes may be involved in the genesis and development of histologically distinct categories of common epithelial tumors of the human ovary.

Adenocarcinoma, Clear Cell↗
PubMed1994

Identification of estrogen receptor in human adipose tissue and adipocytes.

Estrogen has various effects on adipose tissue. Although the presence of estrogen receptor (ER) has been demonstrated in rat adipose tissue and adipocytes, ER has not been identified in human adipose tissue. In this study, we demonstrated the existence of ER protein and ER messenger RNA (mRNA) in human sc adipose tissue and adipocytes. The cytosol fraction of human adipose tissue was partially purified by ammonium sulfate precipitation, and the presence of ER protein was analyzed by [3H]estradiol (E2) binding assay and Western blot analysis. [3H]E2 binding assay showed a low specific binding due to high nonspecific binding, and the dissociation constant (Kd) and maximal binding sites could not be obtained by Scatchard analysis. Western blots, however, showed the presence of ER protein in both the partially purified cytosol and nuclear fractions of human adipose tissue. The mol wt of ER in both fractions was approximately 66,000. Furthermore, Northern blot analysis of total RNA samples isolated from human adipose tissue showed the expression of ER mRNA at 6.2 kilobase in size. ER mRNA was also identified in isolated human adipocytes by the reverse transcription and polymerase chain reaction. These results indicated that both ER protein and ER mRNA are expressed in human adipocytes, suggesting that the effect of estrogen on human adipose tissues might involve a direct action.

Adipocytes↗
PubMed1994

Differential susceptibility of morphologically TPA-resistant and -sensitive Balb/c 3T3 variants to TPA-induced cell transformation: relationship to induction of membrane ruffling.

To investigate the responsiveness to phorbol ester-mediated malignant cell transformation of Balb/c 3T3 variant clones that were morphologically phorbol ester-sensitive and -resistant, we used an in vitro two-stage transformation assay in which cells were treated with 0.1 microgram/ml of MCA as an initiator and subsequently with 12-O-tetradecanoylphorbol-13-acetate (TPA) as a promoter. The morphologically TPA-sensitive variant, TR5, and the parent cells showed a relatively low sensitivity to TPA-induced cell transformation, whereas the morphologically TPA-resistant variant, TR4 cells, exhibited 50- to 100-fold higher sensitivity to phorbol ester-induced cell transformation than the parent or the TR5 cells. We investigated the effects of TPA on protein kinase C activity, 80 kDa PKC substrate phosphorylation, the organization of actin stress fibers, DNA synthesis, and anchorage-independent growth in the three cell clones. They showed similar responses to these biological and biochemical events, indicating that these PKC-mediated events may not be the causes of the differential responsiveness of the variant cells to TPA-induced cell transformation. We further examined their responsiveness to growth factor-mediated and spontaneous induction of membrane ruffling. When these cells were stimulated by PDGF in their growing phase, membrane ruffling was rapidly induced in the three cells. However, the PDGF-mediated membrane ruffling was completely suppressed in parent and TR5 but not TR4 cells in the confluent, contact-inhibited (steady-state) growth phase. Similar responses were observed by other growth factors such as insulin, IGF-I, acidic or basic FGF. In addition, when the cells were cultured beyond confluence in the presence of TPA, spontaneous membrane ruffling was induced continuously up to termination of culture in TR4 but not in parent and TR5 cells. These results suggest that the deficiency in cell contact-mediated inhibition of membrane ruffling may be responsible for hypersensitivity of TR4 cells to TPA-induced cell transformation.

3T3 Cells↗
PubMed1994

Induction of membrane ruffling by growth factors in morphologically TPA-resistant Balb/c3T3 TR4 cells.

To investigate the biological characteristics of a Balb/c3T3 variant TR4 clone which is morphologically resistant to TPA and hypersensitive to v-src induced metastasis, we compared the responsiveness of the variant and its parent cells to growth factor-induced membrane ruffling. When the confluent cells were stimulated with PDGF, membrane ruffling was rapidly induced in TR4 but not in the parent cell cultures. In TR4 cells, membrane ruffling was observed under a phase-contrast microscope within 2 min after the addition of PDGF, reaching the maximum 5 min later and thereafter decreased gradually to the control level. There were no apparent differences in 125I-PDGF binding kinetics between TR4 and parent cells. Similar membrane ruffling was induced by other growth factors such as insulin, IGF-I, acidic or basic FGF but not by EGF or alpha- and beta-TGF, only in TR4 cells. When TR4 cells were incubated with TPA just before stimulation with these growth factors, growth factor-induced membrane ruffling was completely inhibited. Also, 5 out of 6 clones of stable fusion cells between TR4 and parent cells showed the parental type of responses to TPA and growth factors, indicating that the TR4 phenotype is recessive. These results suggest that the variant TR4 cells may acquire the genetic and recessive alteration of a cellular factor which is responsible for the regulation of growth factor-mediated membrane ruffling and that this genetic alteration occurs at a common step downstream of growth factor-mediated cascades, rather than at their receptor level.

3T3 Cells↗
PubMed1994

[Measurement of specific IgE antibody to false cypress (Chamaecyparis obtusa, Hinoki) pollens using Shionoria specific IgE].

A basic and clinical study was carried out to evaluate the usefulness of the Shionoria Specific IgE (SIST) kit for false cypress allergen. The test materials were sera from 152 patients who visited our clinic with symptoms of nasal allergy during the period when Japanese cedar and false cypress pollens are prevalent in the air. The standard curve drawn on the standard serum, which was part of the test kit, was linear. Dilution, inhibition and absorption tests were all satisfactory. Reproducibility studies, different-day, and inter-performers, were all excellent. Nonallergic sera and umbilical cord sera showed less reactivity than the reference serum which is classified as class 0. The sensitivity of the SIST kit for False cypress was 89.9%; specificity 86.3%, and concordance rate 88.2%. The SIST test results for the sera well correlated with the results given by skin tests. These results are good evidence of the excellence of this kit. It was of interest that in the inhibition test, some false cypress positive sera were blocked with Japanese cedar extract as well as with false cypress extract, while other false cypress positive sera were blocked only with false cypress extract. Similar results were obtained in the absorption test. This suggests that the antibodies of some patients recognize a portion of the false cypress allergen which is common to a particular portion of the Japanese cedar allergen.

Adult↗
PubMed1993

Characterization of DNA synthesis at a restrictive temperature in the temperature-sensitive mutants, tsFT5 cells, that belong to the complementation group of ts85 cells containing a thermolabile ubiquitin-activating enzyme E1. Involvement of the ubiquitin-conjugating system in DNA replication.

A temperature-sensitive mutant defective in DNA replication, tsFT5, has been isolated from the mouse mammary carcinoma cell line FM3A. DNA synthesis in tsFT5 cells at a restrictive temperature (39 degrees C) has been characterized in detail. Incorporation of [3H]thymidine decreased rapidly after an increase in temperature to 39 degrees C and the incorporation was less than 20% and 10% of the initial level after 4 and 8 h, respectively. Analysis by DNA fiber autoradiography revealed that the initiation of DNA replication at the origin of the replicons was impaired in tsFT5 cells but that the DNA chain elongation rate of the mutant cells did not decrease at the nonpermissive temperature. tsFT5 cells were confirmed to belong to the complementation group which includes ts85 cells arrested mainly in the G2 phase at the nonpermissive temperature. It has been observed that the amount of ubiquintin-conjugated histone H2A (uH2A) in ts85 cells decreases at the nonpermissive temperature (Marunouchi, T., Yasuda, H., Matsumoto, Y., and Yamada, M. (1980) Biochem. Biophys. Res. Commun. 95, 126-131). The amount of uH2A in tsFT5 cells also decreased rapidly at 39 degrees C. This decrease occurred at the same time as or slightly preceding to reduction in DNA synthesis, and the reappearance of uH2A was followed by the restoration of DNA synthesis after the temperature was reduced. A similar temporal relationship between decrease in the amount of uH2A and reduction in DNA synthesis was observed in ts85 cells cultured at 39 degrees C. However, the rates of the decrease of uH2A and of the reduction in DNA synthesis in ts85 cells were slower than those observed in tsFT5 cells. A comparison of the thermolability of purified ubiquitin-activating enzyme E1s revealed that the E1 from ts85 cells had a thermolability intermediate between those of the E1 from tsFT5 cells and of the wild-type cells. A reduction in the phosphorylation of histone H1 was observed in tsFT5 cells cultured at 39 degrees C, but the reduction occurred several hours after the decrease in uH2A and the reduction in DNA synthesis.

Animals↗
PubMed1993

Alterations of the p53 tumor suppressor gene and its association with activation of the c-K-ras-2 protooncogene in premalignant and malignant lesions of the human uterine endometrium.

We previously reported (T. Enomoto et al., Cancer Res., 50: 6139-6145, 1990; T. Enomoto et al., Cancer Res., 51: 5308-5314, 1991) a significant frequency of activating point mutations in codon 12 of the c-K-ras-2 protooncogene in endometrial adenocarcinoma and its premalignant precursor lesions (series 1 and 2). To reveal the role of the p53 tumor suppressor gene in the development of endometrial adenocarcinoma and to study the association of p53 alterations with K-ras activation, an additional 28 endometrial adenocarcinomas and an additional 11 premalignant atypical uterine hyperplasias (series 3), as well as 12 cases of endometrial adenocarcinoma (10 having K- or N-ras activation) and 2 cases of atypical hyperplasia from series 1 and 2, were screened for the presence of p53 alterations. Allelic loss, recognized at the polymorphic site in codon 72 of the p53 gene, was detected in 6 of 19 (32%) informative cases of endometrial adenocarcinoma and 1 of 4 (25%) informative cases of endometrial atypical hyperplasia by restriction fragment length polymorphism analysis and by single-strand conformation polymorphism analysis of polymerase chain reaction (PCR)-amplified DNA fragments. Mutations in the highly conserved regions of the p53 gene were detected by single-strand conformation polymorphism analysis of PCR-amplified DNA fragments. Mutations were found in 9 of 40 (23%) endometrial adenocarcinomas and 1 of 13 (8%) atypical hyperplasias that were studied. Mutations in p53 were significantly more frequently found in clinical grade 3 (G3) cancers (6 of 14, 43%) than in G1-G2 cancers (3 of 26, 12%) (P = 0.033). Mutations were subsequently confirmed by direct sequencing. Single missense base substitutions were detected in 6 cases of endometrial carcinoma and in one case of atypical hyperplasia. Deletions of a single base and of 2 bases were each detected in single cases of endometrial carcinoma, and a single base insertion was found in a third case. Point mutations in K-ras were also identified in tumors of series 3 by direct sequencing of PCR-amplified DNA fragments of exons 1 and 2. Point mutations in codons 12 and 13 in K-ras were detected by direct sequencing of PCR-amplified DNA in 7 of 28 adenocarcinomas in series 3, but none were found in exon 2 (codons 59.63. The spectrum of point mutations in p53 in endometrial adenocarcinomas was almost identical to what we found in K-ras in series 1 and 2 and in series 3, suggesting the possible role of a mutagen that might be responsible for mutations in both K-ras and p53.(ABSTRACT TRUNCATED AT 400 WORDS)

Adenocarcinoma↗
PubMed1993

Alterations of the Rb gene and its association with Ki-ras activation and p53 inactivation in endometrial adenocarcinoma.

Alterations of the retinoblastoma (Rb) gene were evaluated in nine primary endometrial adenocarcinomas that we had previously analyzed for the presence of Ki-ras activations and p53 alterations and in three endometrial carcinoma cell lines. Loss of mRNA expression in the Rb gene was detected in two of the 12 tumors. Internal deletions of Rb cDNA were observed in two tumors; one was a deletion of exon 21 in a primary carcinoma, and the other was a deletion of exon 8 in one allele in one cell line. Loss of heterozygosity of the Rb gene, which was detectable by polymorphisms in introns 1 and 17, was analyzed using polymerase chain reaction-restriction fragment length polymorphism analysis in 29 endometrial carcinomas. Of 13 heterozygous cases, two cases (15%) showed loss of heterozygosity. We therefore suggest that alteration of the Rb gene, as well as activation of the Ki-ras gene and alterations of the p53 gene, plays a significant role in the etiology of endometrial adenocarcinoma.

Adenocarcinoma↗
PubMed1993

Crouzon disease associated with sinus pericranii: a report on identical twin sisters.

Crouzon disease is a form of craniosynostosis with the autosomal dominant mode of inheritance. Among the anomalies associated with craniosynostosis, aberrant dural sinus is well known. We report on identical twin sisters with Crouzon disease and sinus pericranii who were successfully treated surgically. In one of the sisters hydrocephalus was present, which eventually needed a shunt operation. The association of these anomalies is discussed.

Cephalometry↗
PubMed1993

67Ga citrate and 99mTc(v)-DMSA scintigraphy in a case of maxillary sinus liposarcoma.

Scintigraphic images with 67Ga citrate and 99mTc(v)-dimercaptosuccinic acid and MR image of a 16-year-old male with maxillary sinus liposarcoma (predominantly myxoid type) are reported. The MR image clearly indicated the exact location, size and anatomical relationship of the tumor. Scintigraphic evaluation was useful in suggesting the malignant nature of the tumor and showed no distant metastasis. Both examinations were effective in treating this case.

Adolescent↗
PubMed1993

Low frequency of H-ras activation in naturally occurring hepatocellular tumors of C3H/HeNCr mice.

Previous reports from several laboratories have consistently shown that approximately 30% of spontaneous hepatocellular adenomas and 70-80% of spontaneous hepatocellular carcinomas found in aged B6C3F1 [C57BL/6 (liver tumor resistant) x C3H (liver tumor susceptible)] male mice contain one of three missense point mutations in codon 61 of the H-ras oncogene, CAA-->AAA, CGA or CTA. Irrespective of subline, the C3H mouse, the paternal parent strain of the B6C3F1 hybrid, is more susceptible to spontaneous liver tumorigenesis than the B6C3F1 mouse. However, the role of H-ras in the pathogenesis of hepatocellular tumors in C3H mice is less clear, as widely different frequencies of activation of this gene, but by the same point mutations in codon 61, have been reported by various laboratories. The present study was undertaken to characterize H-ras involvement in hepatocellular tumors of aged C3H/He mice from the NCI-Frederick Cancer Research and Development Center Colony (C3H/HeNCr). Oncogene activation was evaluated in 45 C3H/HeNCr hepatocellular tumors by the NIH 3T3 transfection assays, and point mutations in the H-ras oncogene were detected and characterized in DNA fragments amplified by PCR, using dot blot hybridization analysis with mutation-specific oligonucleotide probes and direct dideoxy sequencing of PCR products. The only transforming gene detected in these tumors by NIH 3T3 transfection was H-ras. Only 17% (1/6) of spontaneous carcinomas and 8% (3/39) of spontaneous adenomas contained transforming H-ras sequences, each with a point mutation in codon 61. In all four cases with H-ras mutations, mutated sequences comprised a minor fraction of total H-ras gene copies in DNA extracted from primary tumors. H-ras mutations thus appear to have arisen relatively late in the pathogenesis of the neoplasms. For comparison, sections of formalin-fixed, paraffin-embedded hepatocellular tumors that occurred in untreated B6C3F1 hybrid mice sired by C3H/HeNCr males were assayed for the same H-ras mutations by PCR and dot blot hybridization. Nine of 13 such tumors (4/6 carcinomas, 5/7 adenomas) were positive. The overall difference in frequency of H-ras codon 61 mutations in hepatocellular tumors in C3H/HeNCr (4/45) versus B6C3F1 (9/13) was highly significant (P = 0.000035, Fisher's exact test). These data indicate that point mutations in H-ras do not generally play a major or an initiating role in spontaneous hepatocarcinogenesis of inbred C3H/HeNCr mice and contrast with the high rate of ras mutations in liver tumors of the B6C3F1 hybrid.

3T3 Cells↗
PubMed1993

Platelet cyclic GMP. A potentially useful indicator to evaluate the effects of nitroglycerin and nitrate tolerance.

BACKGROUND: The present study was designed to investigate the intracellular production of cyclic GMP (cGMP) in platelets in response to nitroglycerin and to determine the potential clinical value of platelet cGMP as an indicator of the effects of nitroglycerin and nitrate tolerance. METHODS AND RESULTS: Platelet cGMP levels and the diameters of the coronary arteries before and 2 minutes after intracoronary injection of 200 micrograms nitroglycerin were measured in 15 patients who had previously received nitrates (nitrates group) and in 16 who had not received any nitrates (no-nitrates group). Platelet cGMP levels increased significantly after nitroglycerin injection in the two groups, but plasma cGMP levels and plasma atrial natriuretic peptide levels did not change. The percent increase in platelet cGMP levels and the percent dilatation of the left anterior descending (LAD) and left circumflex (LCx) coronary arteries after nitroglycerin injection were higher in the no-nitrates group than in the nitrates group (platelet cGMP levels: artery, 74.2 +/- 18.3% versus 11.5 +/- 4.2%, P < .01; vein, 73.6 +/- 22.9% versus 9.0 +/- 3.1%, P < .01; coronary dilatation: LAD, 46.7 +/- 6.0% versus 9.9 +/- 2.5%, P < .01, LCx, 51.2 +/- 8.7% versus 6.1 +/- 3.0%, P < .01). The percent increase in platelet cGMP levels was significantly correlated with the percent dilatation of the coronary arteries (LAD: r = .90, P < .01; LCx: r = .92, P < .01) in the no-nitrates group and not in the nitrates group. CONCLUSIONS: These results indicate that platelet cGMP can be used as an indicator for in situ evaluation of nitroglycerin effects and that patients who have received nitrates develop nitrate tolerance, which affects intracellular production of cGMP and vasodilation in the response to nitroglycerin.

Atrial Natriuretic Factor↗
PubMed1993

Rhabdomyolysis and acute renal failure in a patient with hypothyroidism.

A 61-year-old woman developed rhabdomyolysis and acute renal failure after strenuous walking. She had been treated for seven years with levothyroxine (T4) for hypothyroidism. On admission, her thyroid function test revealed marked hypothyroidism, suggesting poor drug compliance. Electromyographic and muscle biopsy findings were compatible with hypothyroid myopathy. Other diseases that could cause rhabdomyolysis were excluded. Her renal function completely recovered with peritoneal dialysis, and thyroid function normalized with 100 micrograms/day of T4. The present case suggests that rhabdomyolysis could occur in patients with hypothyroidism, especially those with poor drug compliance, in combination with other aggravating factors such as exercise.

Acute Kidney Injury↗
PubMed1993

[Effect of indomethacin on the release of chemical mediators from human peripheral leukocytes].

We studied the effect of indomethacin (IND) on the release of chemical mediators from human peripheral leukocytes and the relation of prostaglandin (PG) E2 and PGI2 to that effect. We stimulated the leukocyte suspensions with calcium ionophore A23187 (CaI, 10(-6) M) accompanied with IND (10(-5) M), PGE2 (10(-5) M) or PGI2 (10(-5) M) and measured the levels in histamine (HA), leukotriene C4/D4/E4 (peptide-LTs) and LTB4 in the supernatant fluid. The increase of HA levels induced by CaI was significantly enhanced by IND (p < 0.01), and the enhancement was significantly inhibited by PGE2 (p < 0.05) and PGI2 (p < 0.01). The release of peptide-LTs was not enhanced by IND and was inhibited significantly by PGE2 (p < 0.05) and PGI2 (p < 0.01). IND did not affect the release of LTB4 induced by CaI. However, LTB4 release was also significantly inhibited by PGE2 and PGI2 (p < 0.01). These results suggest that the inhibitory effect of IND on the production of PGE2 and PGI2 results in the enhancement of HA release. PGE2 and PGI2 have a potent inhibitory effect on the release of HA, peptide-LTs and LTB4 from human leukocytes.

Adult↗
PubMed1992

Thrombocytosis in patients with tumors producing colony-stimulating factor.

We investigated the cause of thrombocytosis in 14 patients with tumors producing colony-stimulating factor (CSF). Of the 14 patients, 10 had tumors producing granulocyte-CSF (G-CSF) and 4 had tumors producing granulocyte-macrophage--CSF (GM-CSF). Thrombocytosis of greater than 400 x 10(9)/L was noted in 8 of 10 patients with G-CSF-producing tumors and all 4 patients with GM-CSF-producing tumors. Median peak platelet counts were, respectively, 511 x 10(9)/L (range, 384 to 694 x 10(9)/L) and 579 x 10(9)/L (range, 526 to 910 x 10(9)/L) in patients with tumors producing G-CSF and GM-CSF. In most patients, thrombocytosis declined towards the terminal stage. High interleukin-1 (IL-1) and IL-6 levels were found in addition to CSFs in the plasma or culture supernatants of tumor cells obtained from most patients. In patients with GM-CSF-producing tumors, these specimens had megakaryocyte-CSF (Meg-CSF) activity, which was abolished by anti-GM-CSF antibody. These specimens also had megakaryocyte potentiating (Meg-Pot) activity attributable to both GM-CSF and IL-6. In patients with G-CSF-producing tumors, only Meg-Pot activity due to IL-6 was detected. These results indicate that the thrombocytosis in GM-CSF-producing tumors was caused by both the Meg-CSF activity of GM-CSF and the Meg-Pot activity of IL-6 plus GM-CSF, while that in G-CSF-producing tumors was due to the Meg-Pot activity of IL-6.

Adult↗
PubMed1992

Alterations of the p53 gene in human primary cervical carcinoma with and without human papillomavirus infection.

A previous report using cervical carcinoma cell lines suggests that the inactivation of two tumor suppressor gene products, p53 and pRB, either by complex formation with the E6 and E7 proteins of oncogenic human papillomaviruses (HPVs) or by mutation, may be an important step in cervical carcinogenesis (M. Scheffner et al., Proc. Natl. Acad. Sci. USA, 88: 5523-5527, 1991). The present study was designed to clarify the association between p53 inactivation and infection with oncogenic HPVs in primary carcinomas of human uterine cervix. We examined 36 primary cervical carcinomas for the presence of HPV DNAs by Southern blot analysis with probes specific for HPV-16, -18, -31, -33, -52, -56, and -58. HPV DNA sequences were detected in 19 of 36 tumors: 10 cases with HPV-16; 3 cases with -18; 3 cases with -58; 2 cases with -56; and one case with -52. The presence of HPV-16 and -18 in cervical carcinomas was further reexamined using polymerase chain reaction. HPV DNA sequences were detected in an additional 10 cases: 9 cases with -16 and one case with -18. The inactivation of the p53 gene by allelic loss or by point mutation was also examined. No allelic loss at the polymorphic site in codon 72 of the p53 gene was detected in any of 10 informative cases. Missense point mutations in the highly conserved regions of the p53 gene were demonstrable as single-stranded conformational polymorphisms of polymerase chain reaction-amplified DNA fragments and subsequently identified by direct DNA sequencing. Point mutations were detected in only two cases: one with an ATG----CTG transversion in codon 133 of exon 5, resulting in a Met----Leu substitution, and another with a CGG----TGG transition in codon 248 of exon 7, resulting in an Arg----Trp substitution. Both tumors with point mutations in p53 genes were among 10 tumors which contained a small copy number of HPV-16 DNA sequences (1 copy of HPV/10(1) to 10(5) cells) detectable by polymerase chain reaction amplification but not by Southern blot analysis of genomic DNAs derived from the tumors. None of 19 tumors with a large copy number of HPV DNA sequences detectable by Southern blot analysis (more than 1 copy of HPV/2 to 10 cells) nor any of 7 tumors with undetectable HPV DNA sequences contained p53 gene mutations in the regions examined.(ABSTRACT TRUNCATED AT 400 WORDS)

Adenocarcinoma↗
PubMed1992

K-ras activation and ras p21 expression in latent prostatic carcinoma in Japanese men.

Twenty-three clinically silent prostatic carcinomas discovered in Japanese men at autopsy were surveyed for ras proto-oncogene mutations by mutation-specific oligonucleotide probe hybridization after polymerase chain reaction (PCR) amplification from a section of formalin-fixed, paraffin-embedded tissue. Six of the 22 that were satisfactory amplified contained activating point mutations in codon 12 of K-ras, a significantly higher frequency than has been reported in patients with clinically advanced disease in the United States. Of the six cases with activating point mutations in codon 12 of K-ras, one had a GGT----GAT transition, four had GGT----GTT transversions, and one had both GGT----GAT and GGT----GTT mutations. Sections from the same tissues were immunohistochemically stained with an anti-ras p21 antibody. Carcinoma cells stained for ras p21 to some degree in 13 cases. Immunohistochemically detectable expression of p21 was always focal and was not necessarily associated with K-ras mutation. K-ras oncogene activation in prostatic carcinoma appears to merit additional study as a significant event in the pathogenesis of this neoplasm.

Aged↗